Application of the Pitzer ion interaction model to isopiestic data for the Fe2(SO4)3-H2SO4-H2O system at 298.15 and 323.15 K>

Tosca, N. J. and Smirnov, A. and McLennan, S. M. (2007) Application of the Pitzer ion interaction model to isopiestic data for the Fe2(SO4)3-H2SO4-H2O system at 298.15 and 323.15 K>. Geochimica Et Cosmochimica Acta, 71 (11). pp. 2680-2698. DOI 10.1016/j.gca.2007.03.020

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Abstract

Recent isopiestic studies of the Fe2(SO4)3-H2SO4-H2O system at 298.15 K are represented with an extended version of Pitzer's ion interaction model. The model represents osmotic coefficients for aqueous {(1 - y)Fe2(SO4)3 + yH2SO4} mixtures from 0.45 to 3.0 m at 298.15 K and 0.0435 b $ y b $ 0.9370. In addition, a slightly less accurate representation of a more extended molality range to 5.47 m extends over the same y values, translating to a maximum ionic strength of 45 m. Recent isopiestic data for the system at 323.15 K are represented with the extended Pitzer model over a limited range in molality and solute fraction. These datasets are also represented with the usual "3-parameter" version of Pitzer's model so that it may be incorporated in geochemical modeling software, but is a slightly less accurate representation of thermodynamic properties for this system. Comparisons made between our ion interaction model and available solubility data display partial agreement for rhomboclase and significant discrepancy for ferricopiapite. The comparisons highlight uncertainty remaining for solubility predictions in this system as well as the need for additional solubility measurements for Fe3+-bearing sulfate minerals. The resulting Pitzer ion interaction models provide an important step toward an accurate and comprehensive representation of thermodynamic properties in this geochemically important system. B) 2007 Elsevier Ltd. All rights reserved.

Item Type: Article
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Geochimica Et Cosmochimica Acta
Volume: 71
Page Range: pp. 2680-2698
Identification Number: 10.1016/j.gca.2007.03.020
Depositing User: Sarah Humbert
Date Deposited: 17 Dec 2009 12:01
Last Modified: 23 Jul 2013 09:56
URI: http://eprints.esc.cam.ac.uk/id/eprint/1254

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